The purpose of this program is to provide the gastroenterologist with a diagnostic screening tool which will enable him to rapidly survey the region of Barrett's esophagus (BE) in a patient with this disease, and allow him to determine with high probability and in real-time, regions of dysplasia and carcinoma. It will be able to distinguish between the categories of adenocarcinoma, high-grade dysplasia, low-grade dysplasia, indefinite for dysplasia and non-dysplastic BE. It will be able to perform measurements of the full length of the esophagus in about ten minutes and provide the information in real time. Suspicious areas can then be biopsied and the diagnosis verified. This approach is vastly superior to the present strategies of performing either systematic or random biopsies. Thus it will provide a powerful tool for screening the large population of Barrett's esophagus patients for early precancerous changes. This instrument will be based on the technique of light scattering spectroscopy (LSS), which has been demonstrated in a proof-of-principle study to be able to perform such measurements in the epithelial tissue of five different organs, including BE. The advantages of the proposed technique are that it greatly simplifies the time and labor involved in performing screening and obtaining diagnoses, will cause less patient discomfort, require fewer biopsies, and it can help the pathologist to base his diagnosis on uniform quantitative criteria, making the diagnosis more consistent. Because of these advantages, it should vastly improve the probability of detecting potential malignancies in the early stages, when cures are possible, and it should be highly cost effective. Since tissue is not necessarily removed, it makes possible progression studies. Such studies may determine accurate predicative factors for the outcome of the disease, and thus simplify the decision in the choice of treatment.